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bioplasticsMAGAZINE_1303

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bioplasticsMAGAZINE_1303

PLA Recycling Recycling

PLA Recycling Recycling ‘hands on‘ The Perpetual Plastic Project with live, interactive demonstration The sustainability and feasibility of various end-of-life options for bioplastics remains a hot discussion topic. The actual application, of course, has a strong influence on which end-of-life option could be the most sustainable. For Purac, Gorinchem, The Netherlands, recycling is the preferred option where possible. This ensures that valuable raw materials remain in the value chain for reuse in future applications. As a result, Purac – a leading company in lactic acid based bioplastics – has sponsored the Perpetual Plastic Project to highlight how easily PLA bioplastic can be recycled. PLA drinking cups were provided by Purac; intended for use at events where people can immediately recycle them into new products after use. The project is designed to educate people on the recyclability of bioplastic, in order to close the loop and promote a circular, biobased economy for future generations. The Perpetual Plastic Project on tour The Perpetual Plastic Project has successfully created a do-it-yourself’, interactive machine, which provides users with a small-scale demonstration of how easily PLA can be recycled: following the steps of cleaning, drying, shredding, melting and extrusion, before finally being remade into a new article. In this case, a 3D printer was used to create jewelry and small toys from the used PLA cups. The machine has toured the Netherlands at numerous events, including the Dutch Design Week in Eindhoven, the Science Center NEMO in Amsterdam and the National Sustainability Congress in Nieuwegein. The Perpetual Plastic Project is an initiative created by former TU Delft students. Purac, together with GroenBeker, provided the PLA bioplastic drinking cups which accompanied the machine. François de Bie, Marketing Director Purac Bioplastics, is pleased with the project: “This initiative demonstrates in a tangible, understandable way just how easily PLA can be recycled. Although PLA is still a relatively new material to the plastics industry, it promises to become widely implemented throughout a broad range of applications. It is therefore vital that we already start to think about how best to recycle these valuable materials. Thanks to the Perpetual Plastics Project, we can show people at events and festivals what can ultimately be achieved on a much larger scale’. Purac has created a short video to highlight the project and the recyclability of PLA. www.purac.com/bioplastics. Info: See http://bit.ly/18SnQiM (or scan the QR-code) to view the video-clip. 54 bioplastics MAGAZINE [03/13] Vol. 8

PLA Recycling Pelletizing and crystallizing of PLA – an analogy to PET?! As PLA finds more and more applications it gives rise to the question of which are the most appropriate technologies for processing. Because of the low glass transition temperature of PLA the crystallization of the plastics may play a decisive role in identifying further processing, depending on the exact material parameters and processing tasks. The strong analogies of PLA and PET concerning water absorption and crystallization behaviour suggest that processes which can be successfully used for the crystallization of PET are also suitable for the processing of PLA. Meanwhile there are some very different methods for the crystallization of PET as virgin and recycled material. An essentially energy-efficient method is the so-called inline crystallization in combination with an underwater pelletizing system, as introduced by BKG Bruckmann & Kreyenborg Granuliertechnik GmbH of Münster, Germany. Complete BKG-KREYENBORG discharge unit consisting of melt pump, screen changer, polymer valve and underwater pelletizing system With the processing of thermoplastics underwater pelletizing systems play an increasingly important role and may slowly replace classic strand pelletizing systems. The spherical pellets, obtained by using a die-face, are the starting point for the following inline crystallization. The cut pellets are transported in extremely hot process water to the centrifugal dryer, in which they are separated from the water. The amorphous pellets exit the dryer at a very high temperature and fall onto a special vibrating conveyor. Under permanent motion, which prevents a sticking together of the hot pellets, the PET crystallizes automatically from inside to outside solely due to the residual heat. Unlike other processes, no additional energy has to be supplied from outside. With the processing of PET a crystallization degree of about 45 % may be achieved. Additionally the pellets do have such a high temperature that further heating for downstream processes is often not necessary. Microscopic picture of PLA resin, which was crystallized with the CrystallCut system of BKG The analogy of PET and PLA is the starting point for a use of this extremely energy-efficient process for the processing of PLA as virgin and recycled material. A direct use depends on the exact parameters and requires an exact adaptation of the process. As soon as this procedure is successfully identified a cost-efficient and energy-saving method for the crystallization is available for PLA processors. Thus the attraction of the forward looking plastic, PLA, is further increased. MT www.bkg.de bioplastics MAGAZINE [03/13] Vol. 8 55

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